This invention relates generally to peristaltic pumps used to deliver fluids to patients by way of a pump set, and more particularly to a peristaltic pump that compensates for physical alteration of the pump set over time to maintain accuracy.
Administering fluids containing medicine or nutrition to a patient is well known in the art. Typically, fluid is delivered to the patient by a pump set loaded on a flow control apparatus, such as a peristaltic pump, which delivers fluid to the patient at a controlled rate of delivery. A peristaltic pump usually comprises a housing that includes a rotor or the like operatively engaged to at least one motor through a gearbox. The rotor drives fluid through the tubing of the pump set by the peristaltic action effected by rotation of the rotor by the motor. The motor is operatively connected to a rotatable shaft that drives the rotor, which in turn progressively compresses the tubing and drives the fluid at a controlled rate through the pump set. The pump set may have a type of valve mechanism for permitting or preventing fluid flow communication through the pump set. A controller operates the motor or motors used to drive the rotor and, if necessary, control fluid flow as by operation of the valve mechanism.
Peristaltic pumps operate by delivering fluid in small charges called “aliquots”. The rotor engages tubing of the pump set, pinching off a portion of the tubing and pushing fluid forward of the pinch point (i.e., closer to the patient than to the source of fluid) toward the patient. Typically, the volume of fluid to be administered to the patient is controlled in the pump by counting the number of aliquots, each being of substantially the same volume, and stopping when the number reaches an amount corresponding to the total desired volume of fluid to be delivered. Peristaltic pumps are sanitary and generally highly accurate and therefore very useful in the administration of medication and therapeutic fluids to the patient. However, the accuracy of the pump is dependent upon the dimensional stability of the tubing of the pump set. Over time the pump set can be plastically deformed so that the volume of each aliquot can change. As a result, the accuracy of the volumes delivered to the patient degrades over the course of the life of the pump set. By way of example, an administration feeding set used for enteral feeding may be used for up to 24 hours.